diff -r 000000000000 -r 6474c204b198 gfx/layers/basic/AutoMaskData.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/basic/AutoMaskData.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_AUTOMASKDATA_H_
+#define GFX_AUTOMASKDATA_H_
+
+#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * Drawing with a mask requires a mask surface and a transform.
+ *
+ * This helper class manages the SourceSurface logic.
+ */
+class MOZ_STACK_CLASS AutoMoz2DMaskData {
+public:
+  AutoMoz2DMaskData() { }
+  ~AutoMoz2DMaskData() { }
+
+  void Construct(const gfx::Matrix& aTransform,
+                 gfx::SourceSurface* aSurface)
+  {
+    MOZ_ASSERT(!IsConstructed());
+    mTransform = aTransform;
+    mSurface = aSurface;
+  }
+
+  gfx::SourceSurface* GetSurface()
+  {
+    MOZ_ASSERT(IsConstructed());
+    return mSurface.get();
+  }
+
+  const gfx::Matrix& GetTransform()
+  {
+    MOZ_ASSERT(IsConstructed());
+    return mTransform;
+  }
+
+private:
+  bool IsConstructed()
+  {
+    return !!mSurface;
+  }
+
+  gfx::Matrix mTransform;
+  RefPtr<gfx::SourceSurface> mSurface;
+
+  AutoMoz2DMaskData(const AutoMoz2DMaskData&) MOZ_DELETE;
+  AutoMoz2DMaskData& operator=(const AutoMoz2DMaskData&) MOZ_DELETE;
+};
+
+}
+}
+
+#endif // GFX_AUTOMASKDATA_H_